S-91253A533 1/4"-20 x 1/4" ASTM F835 Alloy Steel Hex Drive Flat Head Screws

Key Features & Benefits at a Glance

• Superior corrosion resistance with black-oxide coating on alloy steel, extending service life in demanding environments
• Exceptional load-bearing capacity with 130,000 psi tensile strength and Rockwell C39 hardness for reliable performance under stress
• Precise, secure fastening ensured by Class 3A thread fit and UNC coarse threads, reducing the risk of loosening in vibration-prone applications
• Flush, professional finish with 82° countersink angle and undercut flat head design, providing a smooth surface and improved aesthetics
• Efficient installation and removal using a standard 5/32" hex drive, minimizing assembly time and tool wear
• Full-thread engagement along the entire 1/4" length for maximum grip and uniform stress distribution
• Compliance with industry regulations including RoHS 3 and REACH, ensuring safe and sustainable use in global markets

Professional Applications & Engineering Value

This 1/4"-20 UNC flat head screw is engineered to address critical challenges in industrial assembly, such as vibration-induced loosening and material fatigue. The black-oxide alloy steel construction provides enhanced durability and resistance to rust, making it ideal for machinery, automotive, and structural applications where exposure to harsh conditions is common. The fully threaded design and Class 3A thread fit ensure tight, reliable connections that maintain integrity under dynamic loads. With an 82° countersink angle and undercut flat head, it offers a seamless fit that reduces protrusion risks and improves aerodynamic or aesthetic profiles. These features, combined with high tensile strength, make it a trusted choice for engineers seeking long-term performance and reduced maintenance in heavy-duty fastening systems.

Specification Summary & Compliance

This product adheres to precise dimensional standards, including Class 3A thread fit for tight tolerances and UNC coarse threads with a 1/4"-20 size. It meets ASTM F835 specifications for mechanical properties and is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, ensuring environmental safety and material restrictions are upheld.